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Full text of "Alexander von Humboldt"

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46                                  LIFE  OF
the seas of the equinoctial regions of the earth, whore
days and nights are equal. After Dehic had called
attention to the blue colour of the sky in 1765, and
had asked for its cause and conditions, Saussuro in-
vented an instrument in 1791, which he called a
eyanometer-measurer of the blueness of the sky, by
which the degree of the colour is shown on the tables,
arranged on an ascending scale from the palest to the
darkest blue. Humboldt made great use of this in-
strument on this voyage, and ascertained, by the
colour, the degree of blueness, the accumulation and
the nature of the non-transparent exhalations of the
air.
For this purpose he watched the colour and form
of the rising and setting sun, arid ascertained by it the
duration of fine weather, the strength or gentleness of
the wind, and discovered a paleness or unusual diver-
sion of the setting sun to be the infallible sign, of an
approaching storm. He used the instrument also to
measure the colour of the sea, which is generally green,,
and here he also found changes which often turned
the sea during fine weather from the deepest indigo
blue to the darkest green, or slate grey, without any
atmospheric change being perceptible. Ho proved
also that the expression " the ocean reflects the sky/* 
was a purely poetical, but not a scientifically correct*
one* as the sea is often blue when the sky is almost
totally covered with light "white clouds. Beside those
observations Humboldt collected many now facts <m
the moisture of the atmosphere, and on blio electricity
and attraction of the magnetic needle.
Arrived at Oumana, a port in which the traces
of an earthquake which had taken place oi^hiioou
months before were yet to be seen, Humboldt WUB
introduced to the governor of the province by the
captain., and received with great civility, while the
fever~stricken passengers who were brought on shore
found a touching sympathy and ready assistance from
the inhabitants. When Humboldt had seen the
shore, the town, the fortress, a$id the landscape an